(1) Field of the Invention
The present invention generally relates to compositions and methods for reducing odors in absorbent articles. More specifically, the invention is directed to the use of particular compounds in absorbent articles for reducing odors from bodily fluids absorbed in the articles.
(2) Description of the Related Art
References Cited
Baker, L., “An Ounce of Prevention . . . A New Approach to Odor Control for Adult Incontinence”, INSIGHT 2001 Absorbent Products Conference, October 2001.
Smith, J., Wheeler, E., Weiss, R., “Monitoring Ammonia Levels in Livestock Housing”, Herd Health Memo, November 1999.
U.S. Pat. No. 6,376,741 B1.
U.S. Pat. No. 6,369,290 B1.
U.S. Pat. No. 6,342,653.
U.S. Pat. No. 6,229,062 B1.
U.S. Pat. No. 5,769,832.
U.S. Pat. No. 5,733,272.
U.S. Pat. No. 5,591,146.
U.S. Pat. No. 5,429,628.
U.S. Pat. No. 5,103,500.
U.S. Pat. No. 5,079,004.
U.S. Pat. No. 5,037,412.
U.S. Pat. No. 4,842,593.
U.S. Pat. No. 4,059,114.
U.S. Pat. No. 3,920,020.
U.S. Pat. No. 3,691,271.
U.S. Statutory Invention Registration H1,732.
The malodorous gases emanating from used absorbent hygiene articles can be unhealthful and unpleasant to inhale and could be a source of embarrassment to the wearer. Discreetness is a desirable characteristic of an absorbent article to an adult, and part of that discreetness includes the elimination of malodors from the used article. Reduction of the longer-term malodors emanating from the vicinity of the area of disposal of the soiled articles, either in the home or in the institution, is also needed.
It is known that several gases contribute to the malodor resulting from the breakdown of human exudates, such as urine, feces or menses. Of these gases, ammonia is considered to be one of the most potent and recognizable odors associated with aged human exudates, although there are other gases including those of organic acids and sulfur-containing compounds that contribute to malodor. Many prior efforts to diminish malodor from used absorbent articles have focused on reducing ammonia. Ammonia is widely believed to contribute to diaper dermatitis, also known as diaper rash.
Ammonia is produced by the breakdown of urea from urine. Certain bacteria, in the presence of the enzyme urease, digest the urea and produce carbon dioxide and ammonia. But as the bacteria reproduce, more urea is digested, and the malodor (ammonia production) increases with time. It takes hours for ammonia to be produced in significant quantities according to this degradation process. Other odors emanating from urine or waste may be detectable immediately or after short times.
There have been numerous attempts to prevent malodor from used diapers. One category of such attempts involves masking. With masking, another more pleasant odor, such as a perfume, is introduced in such quantities as to overpower the malodor. See, e.g., U.S. Pat. No. 5,769,832. Such methods do not reduce ammonia production, so even if effective masking occurs, the unhealthful inhalation of ammonia gas would continue, and the harmful impact on skin would not be diminished.
Other techniques to reduce odor involve adsorption or absorption. For example, superabsorbent polymer, molecular sieves, activated charcoal, and silica have been used as odor control agents. See, e.g., U.S. Pat. No. 6,376,741 B1. Malodor can also be reduced by eliminating or delaying ammonia production. Included in such methods are agents which act as urease inhibitors, such as sodium tetraborate pentahydrate (U.S. Pat. No. 6,342,653). Methods involving the use of weak acids such as citric acid to lower the pH of the absorbents in the diaper have also been tried. A more acidic pH is known to retard the degradation rate of urea. In addition, sodium bicarbonate has been used to inhibit odors from malodorous organic acids (U.S. Pat. No. 5,037,412). Other methods to reduce ammonia production use antimicrobial agents against bacteria, some in conjunction with lower pH (Baker, 2001). Certain quaternary ammonium compounds are examples of such antimicrobials, which have been used to counter ammonia production from urine (U.S. Pat. No. 4,842,593).
Other publications describing treatment of bodily malodors include U.S. Pat. Nos. 6,369,290 B1; 5,733,272; 5,429,628; 6,229,062 B1; 5,591,146; 5,103,500; 5,079,004; 4,059,114; 3,920,020; and 3,691,271; and US Statutory Invention Registration H1,732.
All of the above-described attempts to reduce malodor have demonstrated limited efficacy or have raised other health or environmental issues or concerns. Hence, there is a need for treatments for absorbent articles such as diapers that allow the articles to be effective in reducing the malodor of bodily fluids exposed thereto, and which are safe to wear and are not unhealthy to the general public. Ideally, the treatment removes odors from the soiled article quickly and should also reduce the odors created over longer periods of time, such as that of ammonia.